Temperature actuated engine spark vacuum control system

ABSTRACT

A two position selector valve alternately connects EGR (exhaust gas recirculation) port vacuum or carburetor spark port vacuum to the engine distributor spark advance control as a function of outside ambient air temperature, to improve vehicle drivability while maintaining a constant emission level.

United States Patent 1191 Sutherland Apr. 2, 1974 TEMPERATURE ACTUATEDENGINE 3,141,447 7/1964 .lernigan .1 123/119 A SPARK VACUUM CONTROLSYSTEM 3,738,108 6/]973 Goto l23/l 17 A Gilbert J. Sutherland, Trenton,Mich.

Assignee: Ford Motor Company, Dearbom,

Mich.

Filed: Dec. 6, 1972 Appl. No.: 312,770

Inventor:

us. 01. 123/117 A, 123/119 A 1m. (:1. F02p 5/04 Field of Search 123/119A, 117 A References Cited UNITED STATES PATENTS 8/1972 Nakajima 123/119A Primary Examiner-Laurence M. Goodridge Assistant ExaminerRonald B. Cox

[57] ABSTRACT A two position selector valve alternately connects EGR(exhaust gas recirculation) port vacuum or carburetor spark port vacuumto the engine distributor spark advance control as a function of outsideambient air temperature, to improve vehicle drivability whilemaintaining a constant emission level.

5 Claims, 2 Drawing Figures TEMPERATURE ACTUATED ENGINE SPARK VACUUMCONTROL SYSTEM This invention relates in general, to an internalcombustion engine in which engine spark timing is controlled as afunction of outside air temperature to control emissions while improvingvehicle drivability.

The introduction of engine EGR (exhaust gas recirculation) to reduce NO,levels in most cases also results in a decrease in vehicle drivequality. The greater the proportion of EGR, the greater bleed of themanifold vacuum signal and a lesser induction of fuel/air mixture intothe engine. This reduces fuel economy and results in poorer fueldistribution into the manifold runners; i.e., exhaust gases enter intothe manifold to one side of the spacer and thus tend to create adifference in flow between the front and rear cylinders.

It is an object of this invention to improve the vehicle drive qualitywhile holding a constant emission level.

In many cases, the vacuum signal for controlling the opening and closingof the EGR valve originates at a port in the carburetor inductionpassage located above the conventional spark port. The EGR port,therefore, sees the vacuum signal later and less often thanthe sparkport, and the signal then is generally smaller.

It is another object of this invention to improve vehicle drivabilitywithout increasing emission levels by using both the EGR and spark portsas alternate vacuum sources for controlling engine distributor advance,the switching between the sources being controlled as a function ofoutside ambient air temperature 'to'provide more advance at lowertemperatures for the same degree of carburetor throttle blade opening.

lt is also an object of the invention to provide an engine controldevice in which a vacuum operated servo controlling the movement of aforce movable member is actuated at times by carburetor spark portvacuum so that the force movable member moves as a function of thedegree of opening of the carburetor throttle valve, switching of thevacuum source from the carburetor spark port to a port higher in theinduction passage effecting a change in the movement of the forcemovable member for the same degree of throttle valve opening, to therebyvary the movement of the force movable member in a desired manner.

Other objects, features and advantages of the invention will become moreapparent upon reference to the succeeding detailed description thereof,and to the drawings illustrating the preferred embodiments thereof;wherein,

FIG. 1 is a schematic illustration of an internal combustion engineemission and spark timing control embodying the invention; and,

FIG. 2 is a cross-sectional view taken on a plane indicated by andviewed in the direction of the arrows 22 of FIG. 1.

FIG. 1 illustrates a portion of one-half of a fourbarrel carburetor of aknown downdraft type. It has an air horn section 12, a main body portion14, and a throttle body 16, joined by suitable means not shown. Thecarburetor has the usual air/fuel induction passages 18 open at theirupper ends 20 to fresh air from the conventional which cleaner, notshown. The passages 18 have the usual fixed area venturies 22cooperating with booster venturies 24 through whieh the main supply offuel is induced, by means not shown.

Flow of air and fuel through induction passages l 8' is controlled by apair of throttle valve plates 26. each fixed on a shaft 28 rotatablymounted in the side walls of the carburetor body.

The throttle body 16 is flanged as indicated for bolting to the top ofthe engine intake manifold 30, with a spacer element 32 located between.Manifold 30 has a number of vertical risers or bores 34 that are alignedfor cooperation with the discharge end of the carburetor inductionpassages 18. The risers 34 extend at right angles at their lower ends 36for passage of the mixture out of the plane of the figure to the intakevalves of the engine.

The exhaust manifolding part of the engine cylinder head is indicatedpartially at 38, and includes an exhaust gas crossover passage 40. Thegases pass from the exhaust manifold, not shown, on one side of theengine to the opposite side beneath the manifold trunks 36 to providethe usual hot spot beneath the carburetor to better vaporize theair/fuel mixture.

As best seen in FIG. 2, the spacer 32 is provided with a worm-likerecess 42 that is connected directly to crossover passage 40 in FIG. 1by a bore 44. Also connected to recess 42 is a passage 46 alternatelyblocked or connected to a central bore or passage 48 communicating withthe risers 34 through a pair of ports 50. Mounted to one side of thespacer is a cup shaped boss 52 forming a chamber 54 through whichpassages 46 and 48 are interconnected.

As described above, it is necessary and desirable to provide some sortof control to prevent the recirculation of exhaust gases at undesirabletimes. For this purpose, passage 46 normally is closed by a valve 56that is moved to an open position by a servo 58. The servo includes ahollow outer shell 64 containing an annular flexible diaphragm 66. Thelatter divides the interior into an air chamber '68 and a signal vacuumchamber 70. Chamber 68 is connected to atmospheric pressure through avent 72, while chamber 70 is connected to a vacuum signal force througha line 74. Line 74 is connected to the carburetor induction passage, ina manner to be described later. The stem 75 of valve 56 is fixed to apair of retainers 76 that are secured to diaphragm 66 and serve as aseat for a compression spring 77 normally biasing the valve to itsclosed position. The stem slidably and sealingly projects through aplate 78 closing chamber 54.

Returning to FIG. 1, a spark port 80 is tapped into the inductionpassage at a point just above or aligned with the idle position ofthrottle valve 26, to be traversed by the edge of the throttle valveduring its opening part throttle movements. This will change the vacuumlevel in spark port 28 as a function of the rotative position of thethrottle valve, the spark port reflecting essentially atmosphericpressure in the air inlet upon closure of the throttle valve. A secondEGR port 82 is located above the spark port so that the latter port seesvacuum later than the spark port because it is uncovered later, for apurpose that will become clear later.

FIG. 1 also shows schematically an engine distributor 84 that includes abreaker plate 86 pivotably mounted at 88 on a stationary portion of thedistributor and movable with respect to a cam 90. The latter has anumber of peaks corresponding to the number of engine cylinders. Eachpeak cooperates with the follower 92 of a breaker point set 94 to makeand break the spark connection in a known manner for each onesixth, inthis case, rotation of cam 90. Pivotal movement of breaker plate 86 in acounterclockwise spark retard setting direction, or in a clockwise sparkadvance setting, is provided by an actuator 96 slidably extending from avacuum servo 98.

Servo 98 may be of a conventional construction. It has a hollow housing100 whose interior is divided into an atmospheric pressure chamber 102and a vacuum chamber 104 by an annular flexible diaphragm 106. Thediaphragm is fixedly secured to actuator 96, and is biased in arightward retard direction by a compression spring 108. Chamber 102 hasan atmospheric or ambient pressure vent, not shown, while chamber 104 isconnected to a vacuum signal line 110. Line 110, in turn, is alsoconnected to the carburetor induction passage in a manner that willbecome clear later.

During engine-off and other operating conditions to be described,atmospheric pressure exists on both sides of the diaphragm 106,permitting spring 108 to force the actuator 96 to the lowest sparktiming advance or a retard setting position. Application of vacuum tochamber 104 moves diaphragm 106 and actuator 96 toward the left to anengine spark timing advance position, by degree, as a function of achange in vacuum level.

Turning now to the invention, the flow of spark port and EGR port vacuumto the EGR servo 58 and to the spark timing control servo 98 iscontrolled in FIG. 1 by a three port electrically controlled selectorvalve 114. Selector valve 114 includes a valve body having first andsecond inlet ports 1 l8 and 120 and one outlet port 122, connectedrespectively by lines 124, 126 and 128 to spark port 80, EGR line 74,and distributor line 1 10. Valve 114 includes a two position slide valve130 biased by a spring 132 to a lower position shown. In this position,it connects spark port vacuum in line 124 through an angled passage 134to distributor line 128, while blocking EGR inlet 120. A solenoid 136,when energized, pushes the valve 130 upwardly to its second position. Inthis position, a U-shaped passage 138 connects the EGR port vacuum line126 through ports 120 and 122 and line 128 to distributor line 110,while blocking port 118.

Solenoid 136 is connected electrically to ground through a connection140, and through a line 142 to a battery or other suitable power source144. A switch 146 located in the line controls the energization ofsolenoid 136,

Switch 146 in this case is an ambient temperature sensitive thermostaticswitch that is closed above, say 58F to complete the circuit, and openswhen the temperature drops below that level. When closed, solenoid 136is energized, and moves valve 130 upwardly. This will switch distributoradvance signal in line 110 from spark port vacuum to EGR port vacuum,and condition the distributor for less advance for the same throttleblade setting. When the temperature drops below 58F., the circuit tosolenoid 136 is broken, and the selector valve is in the position shown.Thus, spark timing advance occurs as a function of throttle valvemovement and spark port vacuum level, which provides better performanceand starting during cold weather operation.

It will be clear of course that other controls can be provided tocontrol the switching function, within the scope of the invention. Forexample, an engine water temperature sensitive switch could besubstituted for the switch 146.

I claim:

1. An engine spark timing and exhaust gas recirculation controlcomprising in combination, a carburetor induction passage having athrottle valve rotatably mounted therein and movable between positionsopening and closing the induction passage, a spark port in the inductionpassage located above the closed position of the throttle valve, anexhaust gas recirculation (EGR) port located in the induction passageabove and axially spaced from the spark port, an (EGR) servo having an(EGR) valve connected thereto and movable by vacuum applied to the servoto control flow of exhaust gases into the engine induction system, firstconduit means connecting the (EGR) port to the (EGR) servo, a secondengine spark timing control servo connected to a spark adjusting memberof an engine distributor movable in opposite directions to advance orretard the spark, second conduit means connecting the spark port to thesecond servo, other conduit means connecting the first and secondconduit means, and selector valve means in the other conduit meansmovable between positions alternately connecting spark port or (EGR)port vacuum to the second distributor servo to vary spark timing advanceand retard for the same degree of throttle valve opening as a functionof the position of the selector valve means, and means to move theselector valve means.

2. A control as in claim 1, including temperature sensitive meanscontrolling the operation of the selector valve means to response to theattainment of a predetermined temperature level.

3. A control as in claim 1, including spring means biasing the (EGR)valve to a closed position, and spring means biasing the spark adjustingmember towards a retard position.

4. A control as in claim 3, including solenoid means connected to theselector valve means and to a source of electrical energy, and othermeans to interrupt or break the circuit between the source and solenoidto control the switching of the second servo vacuum source from thespark port to the (EGR) port and vice versa.

5. A control as in claim 4, the other means comprising a temperatureresponsive on-off switch, and spring means biasing the selector valvemeans to a position connecting spark port vacuum to the second servo.

1. An engine spark timing and exhaust gas recirculation controlcomprising in combination, a carburetor induction passage having athrottle valve rotatably mounted therein and movable between positionsopening and closing the induction passage, a spark port in the inductionpassage located above the closed position of the throttle valve, anexhaust gas recirculation (EGR) port located in the induction passageabove and axially spaced from the spark port, an (EGR) servo having an(EGR) valve connected thereto and movable by vacuum applied to the servoto control flow of exhaust gases into the engine induction system, firstconduit means connecting the (EGR) port to the (EGR) servo, a secondengine spark timing control servo connected to a spark adjusting memberof an engine distributor movable in opposite directions to advance orretard the spark, second conduit means connecting the spark port to thesecond servo, other conduit means connecting the first anD secondconduit means, and selector valve means in the other conduit meansmovable between positions alternately connecting spark port or (EGR)port vacuum to the second distributor servo to vary spark timing advanceand retard for the same degree of throttle valve opening as a functionof the position of the selector valve means, and means to move theselector valve means.
 2. A control as in claim 1, including temperaturesensitive means controlling the operation of the selector valve means toresponse to the attainment of a predetermined temperature level.
 3. Acontrol as in claim 1, including spring means biasing the (EGR) valve toa closed position, and spring means biasing the spark adjusting membertowards a retard position.
 4. A control as in claim 3, includingsolenoid means connected to the selector valve means and to a source ofelectrical energy, and other means to interrupt or break the circuitbetween the source and solenoid to control the switching of the secondservo vacuum source from the spark port to the (EGR) port and viceversa.
 5. A control as in claim 4, the other means comprising atemperature responsive on-off switch, and spring means biasing theselector valve means to a position connecting spark port vacuum to thesecond servo.